The beeper is very cheap insurance.
There's a different one on HobbyKing - depending on your preferences, you might want this one instead: http://www.hobbyking.com/hobbyking/s...dProduct=13064
It can't be triggered by a channel like mine, but it doesn't use up a channel either - instead, it is triggered by a loss of radio signal. So you can turn it on, simply by turning your radio off.
I have tested the beeper in the air, on a still day you can hear it faintly from around 200m away. Note my beeper is mounted outside the plane on the fuselage, rather than inside the battery compartment.